Edit: I assume the VIO server is right for you. Some links no longer work.
Consider whether the Virtual IO Server is right for you
Originally posted September 2010 by IBM Systems Magazine
I attended an OMNI user group meeting a while ago and during the meeting, someone mentioned the difference between attending an education event where you’re familiar with the topic versus a topic you know little about. While you’ll probably learn something at the familiar event, it may only be 1-2 percent added knowledge and a lot of repeated information. But at an event that’s unfamiliar, 50-60 percent of the material may be new to you and it might feel like you’re drinking from a fire hose as you try to digest all of these new ideas and concepts.
At one event, you’re comfortable. At the other, you can feel overwhelmed or wonder why you don’t already know these concepts. Rather than beat yourself up about the knowledge that you haven’t been exposed to yet, see it as an opportunity to learn something new.
Nowhere was that concept clearer at that meeting than during a discussion about whether or not to use the Virtual IO Server (VIOS).
To VOIS or Not to VOIS
Several people had a lively discussion around the pros and cons of virtual IO, but it was clear to me that many were unfamiliar with or misunderstood the capabilities of VIOS. They kept trying to compare VIOS to the managed partition they remembered from years past, which seemed to be all bad memories. They worried about VIOS being a single point of failure or adding a layer of complexity to their server. I’m not certain the IBM i world is fully on board with this solution yet.
At the meeting, it took a while to dispel the myths. Those of us with VIOS experience explained that you can have dual VIO servers so that VIOS is no more of a single point of failure than internal disks would be. With PowerVM virtualization and VIOS, you can continue to add more LPARs to your frame as long as you have available CPU and memory. You don’t have to spend more money for adapters or disks, which leads to lower overall costs compared with dedicated adapters and disks. Using VIOS, you could very easily set up test systems on the same frame as your production systems using this scenario. Rapid provisioning becomes a reality when your environment is virtualized, as you’re not making any changes to physical hardware.
Using VIOS, you could share your storage environment and ‘play nice’ with the rest of the servers in the organization. Instead of people saying that you have an oddball/proprietary/expensive/closed machine sitting in the corner, you can tell them that besides running IBM i, you can also run AIX or Linux—all on the same frame, all sharing the same back-end storage-area network (SAN) and the same network and disk adapters.
Once the meeting attendees understood what you could do with VIOS, and they realized you can pretty much set it up and forget it (until you need to deploy new partitions, and even then it’s a straightforward process), it seemed to me that some warmed up to the idea of virtualizing using VIOS.
More recently, a midrange.com thread entitled “To use VIOS or Not to use VIOS, that is the question” discussed the same types of concerns about complexity and which systems should be primary or guest partitions.
I’ve written twice before on IBM i and VIOS—in a “My Love Affair with IBM i and AIX” blog entry and an article called “Running IBM i and AIX in the Same Physical Frame”—and I think the whole issue boils down to time, availability and training. It takes time to get comfortable with something new. None of us started working on IBM i and were experts in it within a week. It took time to become proficient. The same can be said for VIOS. If you come from a UNIX background, it can help, but the padmin user interface is foreign even to AIX administrators the first time they log into it. Things are just different enough that AIX admins have to learn the padmin/VIOS interface the same way that IBM i admins do. One great resource to start with is the VIO Cheat Sheet.
Real-World Experience
How do you learn VIOS if you don’t have VIOS to play with? Without a test box to work on it can be difficult to learn and understand. You can read IBM Redbooks publications such as “Virtual I/O Server Deployment Examples” and attend lectures on the topic (I recommend the Central Region Virtual Users group, for replayed lectures on many topics, including VIOS configuration overviews), but without hands on experience, it can be difficult to become proficient. I’d argue that this is the same as hiring a new IBM i admin, but then asking him to read manuals and Redbooks publications, without ever letting him log into the machine. He’ll probably not be very effective. With time, access to a server running VIOS and training, anyone can become comfortable with it.
Recently, a customer had a new POWER7 770 server that they were adding 25 AIX and two VIOS partitions to. No problem. I loaded VIOS on the internal disks, and the AIX partitions all booted from SAN. They wanted to get their feet wet with IBM i on the 770, and they wanted to see how it would perform using SAN disks instead of internal disks. No problem. I assigned the proper CPU and memory like I would for any new partition, but I didn’t assign any real IO devices. I assigned it virtual SCSI adapters and a virtual network adapter. It was getting its disk from a SAN. It was going to boot from SAN. I didn’t even use physical media to install it; I just used a virtual optical device in the VIO server and booted the LPAR from there. I used the open source tn5250 program to connect to the console, and we were able to load IBM i on the machine to test it out. They were very pleased with the performance that they saw with the SAN and the POWER7 server.
Make an Informed Decision
Of course, one size doesn’t fit all and there are plenty of great reasons to exclude VIOS from your environment. Maybe you don’t have the need for multiple workloads or virtualization on Power hardware. Maybe you don’t have a SAN in your environment and don’t see one coming any time soon. But don’t let fear of the unknown or memories of the way things once were steer your current thinking around virtualization. Make yourself aware of the pros and cons, and make an informed decision.